Conventionally, as a movable finger for an upper extremity prosthesis, a movable finger for an active upper extremity prosthesis has generally been known. As to this movable finger, bases of three or five fingers, which are formed to be slightly bent in fixed shapes respectively, are swingably supported on the back or the palm of an upper extremity prosthesis. These fingers are connected to a linkage mechanism provided inside the back and the palm of the hand, a control lead made of wire is set around the back of a person wearing the upper extremity prosthesis, one end of the control lead being connected to the linkage mechanism. The other end of the control lead is connected to an arm of a side opposite to the side of fixing the upper extremity prosthesis. The control lead is pulled or loosened by moving the arm, and accordingly the three or five fingers are bent or returned by simultaneously swinging all the fingers at the bases thereof by the linkage mechanism.
However, the movable finger for an active upper extremity prosthesis cannot perform any operations other than the simple one of simultaneous bending or returning of the three or five fingers by swinging only at their bases. Consequently, there is a problem that the degree of freedom is too low compared with that of a real hand. In addition, since it is necessary to keep the control lead made of wire attached to the back of the person in wearing the upper extremity prosthesis, there is also a problem that uncomfortableness is felt at the back. 